Two types of vehicle wash systems are in common use. The first type is conveyorized or "tunnel" wash systems, wherein the vehicle is washed while it is in motion. Generally, a vehicle owner drives his/her vehicle onto a conveyor which carries the vehicle through a tunnel. As the vehicle travels through the tunnel, wash apparata suspended from the walls of the tunnel wet the vehicle, apply cleaning and coating agents, brush the vehicle, rinse the vehicle, etc. Conveyorized wash systems occupy substantial space are expensive to build and maintain, largely because their conveyor systems, which are critical to operation, require a high degree of care. Additionally, conveyorized wash systems must generally have an operating technician present while running in case problems arise during washing.
A second form of wash system is the in-bay system, which is used to wash vehicles while they are stationary. The in-bay system utilizes a wash bay situated within a short tunnel or a supporting framework. The tunnel walls (or other supporting framework) support wash apparata about the sides of a stationary vehicle, which can be driven into and parked within the wash bay. The wash apparata are then actuated to wash the vehicle. Two types of in-bay systems are in common use.
The first type of in-bay wash system is the in-bay manual wash system, wherein boom- or carriage-mounted nozzles may be manually positioned in convenient locations by vehicle owners standing within the bay and outside their vehicles, and may then be manually actuated to wash their vehicles. In-bay manual wash systems have become increasingly popular in recent years owing to their relatively low installation and maintenance costs and their ability to be left for vehicle owners' usage without the presence of operating technicians. These factors allow lower usage fees to be passed on to vehicle owners.
The second type of in-bay wash system is the in-bay automatic wash system, wherein wash apparata move about the wash bay (and the vehicle) independently of the vehicle owner's control to automatically execute a wash routine. Alternatively, wash apparata may be stationary within the wash bay and may be so configured that they can still adequately reach and wash most areas of a vehicle within the bay. One common in-bay automatic wash system manufactured by PDQ Manufacturing (Green Bay, Wis., USA) utilizes a carriage which is slightly wider than the standard width of a vehicle, and which rides through the length of the tunnel upon ceiling-mounted tracks. A nozzle-bearing vertical arm (often referred to as a "tower") is mounted on a slide affixed to the carriage so that the slide allows the arm to traverse the width of the tunnel. During a wash routine, the carriage and slide move the arm so that it orbits the vehicle within the drive-in bay and sprays it with water, cleaning agents, coating agents, and air at the appropriate times. Differently-sized vehicles may be automatically accounted for by measuring each vehicle with photoelectronic sensors or other appropriate sensors prior to washing. Such in-bay automatic tower wash apparata are often used in combination with floor-mounted sprinklers which also wash the underside of a vehicle.
In-bay automatic systems, like conveyorized systems, are popular among vehicle owners because they need not leave their vehicles or risk getting wet by manually washing their vehicles. They are also popular among proprietors of vehicle washing establishments because two to four in-bay automatic systems can be installed in the same space as an average conveyorized system, and thus they allow higher throughput of vehicles and greater customer turnaround. However, in-bay automatic wash systems also suffer from several disadvantages.
Initially, since in-bay automatic wash systems must perform all of the activities of conveyorized systems in a far smaller space and while their components are in motion, in-bay systems require greater mechanization and more sophisticated control systems, and are thus quite expensive.
Additionally, in order to save the space that would be occupied by multiple nozzles and fluid delivery systems, in-bay systems should ideally be able to deliver water, cleaning agents, coating agents, and/or other chemicals through the same nozzles. This requires a far more complicated fluid mixing, transport, and delivery system than a conveyorized system, which can use separate fluid delivery systems situated at different points of the conveyorized route to apply different fluids. The problem with using the same mixing, transport, and delivery system for different wash agents is that a system which is well-suited for handling water may not be well-suited for handling detergents, waxes, etc. having significantly different properties (i.e., viscosities, densities, miscibilities, surface tensions, application temperatures, corrosivities, and the like). The situation is compounded in that manufacturers of vehicle washing agents, rather than trying to develop a single "universal" wash agent which will accommodate all washing, coating, etc. needs, are instead involved in efforts towards greater discretization of washing agent functions: they are producing multiple chemicals for application to vehicles at different times or through different nozzle sets, with each chemical providing a different function in the washing process. An example of such chemicals is the TRIPLESHINE chemicals manufactured by Turtle Wax (Chicago, Ill., USA), which is a trio of highly concentrated foaming chemicals which are mixed with water and applied through separate nozzle sets or at separate times during the wash process. The three TRIPLESHINE chemicals respectively include a grime-removing agent, a protective coat and shine agent, and a ultraviolet inhibitor agent. TRIPLESHINE products are extremely effective and are in demand from both wash system proprietors and users, but they are difficult to apply in in-bay systems. The greatest difficulty arises from their foaming properties. When applied through standard in-bay systems, foam formation tends to cause changes in the line pressure of the fluid mixing and delivery system, which in turn affects the mixing ratios of the chemicals and water. Nozzles first begin spraying, then foam builds so heavily that the generated back pressure interrupts spray, then non-foamed chemical-weak fluid is ejected because the high line pressure decreases chemical delivery, and the process then repeats itself as line pressure drops. Throughout this period, the water/chemical composition of the spray varies widely. This effect is amplified owing to the fact that most pumping systems suitable for accurately metering small amount of chemicals deliver the chemicals in a "pulsed" fashion, that is, chemicals are accurately delivered when flow rates are averaged over larger timespans, but chemical delivery varies widely over shorter timespans owing to pump intake and output cycling. Even where pump cycles are spaced apart by only a second or so, this can significantly affect consistency because "rich" charges of chemical will foam dramatically upon mixing with air and thus have a significant impact on line pressure.
Another problem is that foaming products are often sprayed at such a weak pressure that their cleaning power is greatly diminished. It is conventional for many in-bay systems to simply use water from standard municipal water supplies at standard supply pressure (approximately 60 PSI). Products which foam prior to or at ejection can raise the back pressure on the line to such an extent that ejection pressure is greatly decreased, resulting in weak spray.